Furnace for heating metal goods

ABSTRACT

The invention pertains to a furnace for heating metal goods.

FIELD OF THE INVENTION

The invention pertains to a furnace for heating metal goods.

BACKGROUND OF THE INVENTION

Furnaces for heating metal goods are known in the form of reheatingfurnaces and heat treatment furnaces for semi-finished metal products orfor tubes of steel or nonferrous metals. In such furnaces, thecorresponding metal goods are heated for a subsequent hot-formingprocess, a quenching process or for carrying out a thermal process inthe furnace.

In this description, the term metal goods consequently refers tosemi-finished metal products or metal tubes. Semi-finished metalproducts may consist of billets, blooms or slabs.

Popular designs of such furnaces for heating metal goods are pusherfurnaces and walking beam furnaces.

In pusher furnaces, the metal goods lie on rails within the furnacechamber and are pushed through the furnace by means of a pushingmechanism. In this case, the individual metal goods tightly adjoin oneanother such that the pushing mechanism advances the entire furnacecontent when a new metal item is pushed in.

In a walking beam furnace, the transport system for transporting themetal goods through the furnace chamber comprises two types of tubes orbeams. The first type of these tubes or beams, which are also referredto as fixed systems (and comprise horizontal and vertical tubes and/orbeams), are immovable and serve for supporting the metal goods. Thesecond type of tubes or beams, which are also referred to as liftingsystems (and once again comprise horizontal and vertical tubes and/orbeams), move up and down between the fixed systems along anapproximately circular or rectangular path. The metal goods lying on thefixed systems are lifted, advanced by a certain distance and then onceagain deposited onto the fixed systems by means of the lifting systemsduring each of the cyclic motions along the path.

Correspondingly designed furnaces for heating metal goods, particularlypusher furnaces and walking beam furnaces, typically have a furnacechamber with an essentially tunnel-like shape, i.e. with an input sideon one end and an output side on the opposite end of the furnacechamber. In order to fire the furnace chamber, roof burners are arrangedon the ceiling of the furnace above the transport plane of the metalgoods being transported through the furnace chamber (the so-called“upper furnace”) and/or lateral burners are arranged on the sidewalls ofthe furnace. Lateral burners are also arranged on the sidewalls of thefurnace underneath the transport plane of the metal goods beingtransported through the furnace chamber (the so-called “lower furnace”).Since additional firing of the furnace chamber is typically required inthe holding zone of the furnace, i.e. in the region of the furnacechamber situated adjacent to the output side, additional burners in theform of so-called end burners are typically arranged in the upper and/orlower furnace on the end wall of the furnace at the output side.

Furnaces for heating metal goods are usually divided into at least threezones, namely into an input zone (that is also referred to as“convective zone” in the prior art), a heating zone and a holding zone.

The input zone is situated directly adjacent to the furnace inlet andserves for preheating metal goods introduced into the furnace chamber.The input zone is typically not heated by means of burners, but ratherthe hot flue gases extracted from the holding and heating zones.

The heating zone follows the input zone referred to the transportdirection of the metal goods being transported through the furnacechamber. The essential heating or heat treatment of the metal goodstakes place in this heating zone of the furnace chamber. For thispurpose, the heating zone is fired with lateral burners or roof burnersin the upper furnace and with lateral burners in the lower furnace.Since firing of the upper furnace can in the heating zone of the furnacechamber typically be realized in a simpler and more cost-efficientfashion with lateral burners than with roof burners, it is attempted tolargely heat by means of lateral burners in the heating zone. However,this is only possible up to a maximum furnace width because asufficiently uniform temperature distribution over the entire width ofthe furnace can no longer be achieved with lateral burners if thefurnace width exceeds a certain value. Consequently, the upper furnaceof the heating zone is fired by means of roof burners if the furnacewidth exceeds a certain value because a uniform temperature distributionover the entire width of the furnace can be achieved with roof burners.However, a uniform temperature distribution cannot be adjusted in thelower furnace by means of these roof burners.

The holding zone extending up to the furnace outlet follows the heatingzone referred to the transport direction of the metal goods beingtransported through the furnace chamber. In the holding zone, the upperfurnace is typically fired by means of roof burners, lateral burners orend burners and the lower furnace is fired by means of lateral burnersor end burners.

Correspondingly designed furnaces for heating metal goods basically havestood the test of time. In heating furnaces of the above-described type,however, it would frequently be desirable to achieve a more uniformtemperature distribution than that attainable with lateral burnersaccording to the prior art in the lower furnace of the heating zone.This respectively applies, in particular, to furnaces with a significantwidth and to the heating of metal goods with a great length that need tobe heated in correspondingly wide furnaces.

The invention is based on the objective of providing a furnace forheating metal goods that makes it possible to fire the heating zone ofthe furnace in an improved fashion. It should particularly be possibleto realize a more uniform temperature distribution than in furnacesaccording to the prior art in the lower furnace of the heating zone,particularly in furnaces with a significant width.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a furnacefor heating metal goods, said furnace comprising:

a furnace chamber that is designed for accommodating metal goods;

an input side with a furnace inlet, through which the metal goods to beheated in the furnace chamber can be introduced into the furnacechamber;

an output side with a furnace outlet, through which the metal goodsheated in the furnace chamber can be removed from the furnace chamber;

a ceiling that defines the top of the furnace chamber between the inputside and the output side;

a furnace floor that defines the bottom of the furnace chamber betweenthe input side and the output side;

sidewalls that laterally define the furnace chamber between the inputside and the output side;

burners for firing the furnace chamber, wherein the burners comprise atleast one of the following types of burners: roof burners arranged inthe region of the ceiling or lateral burners arranged in the region ofthe sidewalls; and

additional burners for firing the furnace chamber that are arranged inthe region of the furnace floor.

The basic idea of the invention is comprised of firing the furnacechamber of the furnace by means of additional burners that are arrangedin the region of the furnace floor (and referred to as “additionalburners” herein). Since the additional burners are arranged in theregion of the furnace floor, the lower furnace of the inventive furnacecan be fired by means of the additional burners. The lower furnace canbe fired over the entire furnace width in the region of the heating zoneof the inventive furnace by means of the additional burners provided inaccordance with the invention because the arrangement of the additionalburners in the region of the heating zone of the lower furnace is—incontrast to the lateral burners used in the prior art for firing thelower furnace in the region of the heating zone—not limited to thesidewalls, but the additional burners rather may be arranged in theregion of the furnace floor over the entire furnace width in the heatingzone of the furnace. This makes it possible to achieve a much moreuniform temperature distribution in the region of the lower furnace ofthe heating zone than in furnaces according to the prior art, in whichthe heating zone can only be fired by means of lateral burners.

A furnace according to the present invention (hereinafter referred to as“an invention furnace” or “the inventive furnace”) preferably featuresan input zone, a heating zone and a holding zone. These zones may berespectively realized in accordance with the prior art and as describedabove, wherein the lower furnace of an inventive furnace can—in contrastto the prior art—also be fired by means of the additional burners.

The additional burners are preferably arranged in the region of theheating zone of the inventive furnace. According to an embodiment, it isproposed that the additional burners are exclusively arranged in theregion of the heating zone of the furnace.

The burners are preferably not oriented upward, i.e. in the direction ofthe goods to be heated in the furnace, but rather in at least one of thefollowing directions: in the direction of the output side or in thedirection of the input side of the furnace. This makes it possible toachieve a particularly uniform temperature distribution. The uniformityof the temperature distribution can be additionally improved in that theadditional burners, which are respectively oriented in one direction,extend parallel to one another such that the flames or burner gas jetsgenerated in one direction by the additional burners extend parallel toone another.

Since the additional burners are arranged in the region of the furnacefloor, the furnace operation, particularly the flue gas conveyance andthe transport of the goods through the furnace, is not negativelyaffected by the additional burners.

For example, the furnace floor of an inventive furnace does not have tobe designed in a special way in order to accommodate the additionalburners. For example, the furnace floor of an inventive furnace mayessentially be realized in the form of a horizontal plane. This allows aparticularly uniform flame orientation and flue gas conveyance in thelower furnace.

The inventive furnace may be realized, in particular, in the form of apusher furnace or a walking beam furnace. In this respect, the inventivefurnace may feature the characteristics of a pusher furnace or a walkingbeam furnace according to the prior art.

The inventive furnace is designed for heating metal goods, particularlymetal goods of great length—for example in the form of semi-finishedsteel products such as billets, ingots or slabs or in the form of metaltubes.

The inventive furnace and its furnace chamber may basically have anysize and dimension. However, an inventive furnace preferably features avery wide furnace chamber because the advantageous effect of theadditional burners that allow a particularly uniform temperaturedistribution in the lower furnace—especially in the region of the lowerfurnace of the heating zone—manifests itself, in particular, in furnacesof great width.

For example, the width of the furnace chamber of the inventive furnace,i.e. the average clearance between the sidewalls, may amount to morethan 15 m.

The furnace chamber of an inventive furnace may have a length, forexample, of 13 m or more, wherein the length of the furnace refers tothe shortest distance between furnace inlet and furnace outlet in thefurnace chamber.

All burners of the inventive furnace may be realized in accordance withthe embodiments of burners known from the prior art. For example, theburners may consist of high-velocity burners or impulse burners.

The end burners, roof burners and lateral burners of the inventivefurnace may be arranged in accordance with the prior art. In thisrespect, it would be possible, for example, that the furnace features noburners in the region of its input zone. In the region of the heatingzone, the furnace may feature, for example, either roof burners orlateral burners in order to fire the upper furnace; if the inventivefurnace has a great width, it would also be possible that it onlyfeatures roof burners for firing the upper furnace in the region of theheating zone. In order to fire the lower furnace, it is preferred thatthe furnace exclusively features the additional heaters in the region ofthe heating zone. In the region of the holding zone, the inventivefurnace preferably features roof burners, lateral burners or end burnersin order to fire the upper furnace; it is preferred that the furnaceexclusively features one of these three types of burners for firing theupper furnace in the region of the holding zone. The furnace may featurelateral burners or end burners in order to fire the lower furnace in theregion of the holding zone; if the inventive furnace has a great width,it would be possible to exclusively provide end burners for firing thelower furnace in the region of the holding zone.

The furnace may be realized, in particular, in such a way that thefurnace chamber can be heated to temperatures in the range between 500°C. and 1300° C., particularly in the region of the heating zone. If thefurnace is used for heating metal tubes or semi-finished products formetal tubes, the furnace chamber may be designed, for example, for beingheated to temperatures in the range between 500° C. and 1050° C.; inorder to heat other semi-finished metal products, for example, in theform of billets, ingots or slabs, the furnace chamber may be designed,for example, for being heated to temperatures in the range between 950°C. and 1300° C.

As in the prior art, the furnace preferably operates in accordance withthe counterflow principle, wherein the metal goods are transported fromthe furnace inlet in the direction of the furnace outlet and the fluegases generated in the holding zone and the heating zone are conveyed inthe opposite moving direction toward the furnace inlet and extractedfrom the furnace chamber at this location. In the region of the inputzone of the furnace, part of the thermal energy contained in the fluegases is transferred to the metal goods being introduced into thefurnace and these metal goods are thusly pre-heated.

The inventive furnace may feature a device for transporting or guidingthe metal goods through the furnace chamber according to the prior art.Consequently, the furnace may therefore feature a pushing mechanism ifthe inventive furnace is realized in the form of a pusher furnace or acorresponding lifting device for transporting the metal goods throughthe furnace chamber if the furnace is realized in the form of a walkingbeam furnace.

For example, the additional burners of the inventive furnace may bearranged directly in the region of the furnace floor, for example inaccordance with roof burners, lateral burners or end burners known fromthe prior art. In order to purposefully orient the additional burners inthe direction of the furnace inlet or furnace outlet, however, theadditional burners may be arranged in at least one housing disposed inthe region of the furnace floor. In this way, the additional burners canbe arranged in this at least one housing in such a way that they areprotected from the hot furnace atmosphere by the housing, but still canbe purposefully oriented, in particular, in the direction of the furnaceinlet or furnace outlet. These housings may be comprised, for example,of a refractory ceramic material such as a high alumina refractorymaterial.

According to an embodiment, one or several additional burners may berespectively arranged in one housing, wherein several of these housingsmay be arranged, for example, at a distance from one another in theregion of the furnace floor. However, it would also be conceivable, forexample, that all additional burners are arranged in a single housing.

The additional burners may basically be arranged in any position in theregion of the furnace floor. However, it is preferred that theadditional burners are arranged in the region of the furnace floor overthe entire width thereof, particularly over the entire width of thefurnace floor in the region of the heating zone of the furnace.

The additional burners may essentially be arranged, for example, along asection that essentially extends parallel to the furnace outlet in theregion of the furnace floor. The additional burners are preferablyarranged along such a section in the region of the furnace floor, forexample, from one sidewall to the other sidewall, i.e. over the entirewidth of the furnace floor, such that they are equidistantly spacedapart from one another. For example, if the additional burners arearranged in at least one of the aforementioned housings, the housing orthe housings may also extend along such a section, for example, from onesidewall to the other sidewall.

According to the prior art, the metal goods can be transported throughthe furnace chamber in the region of a plane. This transport plane maybe defined by supporting means, on which the goods lie during thetransport through the furnace. If the furnace is realized in the form ofa pusher furnace, the supporting means may consist, for example, ofrails or similar means, on which the goods lie while they are pushedthrough the furnace chamber by the pushing mechanism. These rails may bewater-cooled in accordance with the prior art and protected from thefurnace atmosphere by refractory ceramic masses. It would also bepossible, for example, to use non-cooled rails of heat-resistant steel.

If the furnace is realized in the form of a walking beam furnace, forexample, the transport plane, along which the metal goods aretransported through the furnace chamber, may be defined by the plane inwhich the metal goods are situated when they lie on the fixed systems.The fixed systems and the lifting systems of the walking beam furnacemay likewise be realized in accordance with the prior art, i.e. they mayonce again be comprised of, for example, of water-cooled tubes or railsthat may be protected from the furnace atmosphere by a refractoryceramic mass. It would also be possible, for example, to use non-cooledfixed systems and lifting systems of heat-resistant steel.

Accordingly, the inventive furnace may feature, for example, thefollowing additional characteristics:

a plane, along which metal goods to be heated in the furnace chamber canbe guided through the furnace chamber, wherein the plane divides thefurnace chamber into an upper furnace space (“upper furnace”) that liesbetween the plane and the ceiling and a lower furnace space (“lowerfurnace”) that lies between the plane and the furnace floor;

at least one housing, in which the additional burners are arranged;

wherein the clearance between the upper side of the at least one housingand the underside of the plane amounts to at least 40% of the height ofthe lower furnace space.

Since the clearance between the upper side of the housing or thehousings and the underside of the plane amounts to at least 40% of theheight of the lower furnace space, the flue gas conveyance and thetransport of the metal goods through the furnace chamber are practicallynot influenced. In this respect, it would also be possible, for example,that the clearance between the upper side of the at least one housingand the underside of the plane amounts to at least 50%, 60%, 70%, 80% oreven at least 90% of the height of the lower furnace space.

In technical terminology, the upper furnace space is also referred to as“upper furnace” and the lower furnace space is also referred to as“lower furnace.”

In this description, the height of the lower furnace space or the heightof the lower furnace is the average clearance between the transportplane of the semi-finished products and the furnace floor.

The clearance between the upper side of the at least one housing and theunderside of the transport plane may amount, for example, to at least0.5 m, 0.7 m, 0.9 m, 1.0 m, 1.1 m or 1.2 m. The clearance between theupper side of the at least one housing and the underside of thetransport plane may furthermore amount to no more than 2.0 m, 1.8 m, 1.6m, 1.5 m or 1.4 m.

The height of the lower furnace may lie, for example, in the rangebetween 0.8 and 2.7 m.

According to the invention, it was determined that the furnace operationis practically not affected by the housing or the housings if theclearance between the upper side of the at least one housing and theunderside of the transport plane is correspondingly chosen. For example,the free cross section of the lower furnace required for enabling thehot flue gases generated in the holding zone and in the heating zone topass to the input zone is not substantially narrowed.

Another advantage of a correspondingly large clearance between the atleast one housing and the transport plane can be seen in that any slagaccumulating on the housings cannot come in contact with the metal goodsbeing transported through the furnace chamber or the lifting systems.

According to an embodiment, it is proposed that the furnace features aservice channel that is arranged completely or essentially underneaththe furnace floor and serves for operating the additional burners. Theservice channel may be realized, in particular, in the form of a walk-inchannel for the personnel. For example, it would be conceivable that theadditional burners or the housing or the housings, in which theadditional burners are arranged, can be accessed from the ceiling of theservice channel in order to operate or service the burners.

According to an embodiment, it is proposed that the inventive furnacefeatures flue gas supply means for supplying the additional burners withflue gases, i.e. combustion gases of the burners of the furnace.

Such flue gas supply means have the particular advantage that the fluegases supplied to the additional burners with the aid of the flue gassupply means can be subjected to afterburning by the additional burnerssuch that a reduction of nitrogen oxides can be achieved in the fluegas.

If the additional burners are arranged in at least one housing asdisclosed herein, the flue gas supply means may simply be comprised, forexample, of an inlet or of an opening, via which the flue gases can besupplied to the additional burners through the housing or the housings.For example, the flue gas supply means may comprise flue gas lines, bymeans of which flue gas can be supplied to the additional burners. Ifthe additional burners are arranged in at least one housing, it would beconceivable that such flue gas supply means in the form of theaforementioned openings or flue gas inlets of the aforementioned fluegas lines are arranged on the side of the housing that faces away fromthe burner outlet of the additional burners. In this way, flue gas canbe extracted from the furnace chamber in the region between theadditional burners and the furnace inlet with the aid of the flue gassupply means and supplied to the additional burners such that these fluegases can be subjected to afterburning by the additional burners.

According to an embodiment, the inventive furnace may feature thefollowing additional characteristics:

auxiliary burners for firing the furnace chamber that are arranged inthe region of the furnace floor between the additional burners and theinput side.

These auxiliary burners (in the following referred to as “auxiliaryburners”) may be arranged, in particular, in such a way that the heatingzone of the furnace can also be fired with these burners.

Such an embodiment is particularly advantageous for furnaces with such agreat width, for example, that the furnace chamber also cannot be firedin such a way that the heating zone has the desired temperature or thedesired uniform temperature distribution, particularly in the lowerfurnace, by means of the inventive additional burners.

In other respects, the auxiliary burners may be realized in accordancewith the additional burners, i.e. they may be arranged, in particular,in at least one housing that may be realized in accordance with the atleast one housing of the additional burners. The at least one housing ofthe auxiliary burners may furthermore have the same clearance from thetransport plane as the at least one housing, in which the additionalburners are arranged.

Furthermore, the auxiliary burners can be operated from a servicechannel that may be realized in accordance with the service channel foroperating the additional burners.

The auxiliary burners may furthermore feature flue gas supply means thatare realized in accordance with the flue gas supply means for supplyingflue gases to the additional burners. In contrast to the flue gas supplymeans for supplying flue gas to the additional burners, the flue gassupply means for supplying flue gas to the auxiliary burners can extractflue gas from the furnace chamber in the region between the auxiliaryburners and the additional burners and supply this flue gas to theauxiliary burners.

All characteristics of the inventive furnace disclosed herein may bearbitrarily combined with one another individually or in combination.

An exemplary embodiment of an inventive furnace is described in greaterdetail below with reference to the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a highly schematic sectional view of an inventive furnace,and

FIG. 2 shows a perspective view of a detail of the furnace according toFIG. 1 in the region of the additional burners.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The exemplary embodiment shows a furnace in the form of a walking beamfurnace that is identified as a whole by the reference symbol 1 inFIG. 1. The furnace 1 features an essentially tunnel-shaped furnacechamber 3 for accommodating metal goods. On one end - namely the rightend in FIG. 1—the furnace 1 features an input side 5 with a furnaceinlet 7, through which metal goods to be heated in the furnace chamber 3can be introduced into the furnace chamber 3. On its opposite end—namelythe left end in FIG. 1—the furnace 1 features an output side 9 with afurnace outlet 11, through which metal goods heated in the furnacechamber 3 can be removed from the furnace chamber 3. Between the inputside 5 and the output side 9, the top of the furnace chamber 3 isdefined by a ceiling 13 and its bottom is defined by a furnace floor 15.The furnace chamber 3 is laterally defined between the input side 5 andthe output side 9 by two sidewalls that essentially extend parallel tothe plane of projection, wherein only the sidewall 16 facing away fromthe plane of projection, but not the sidewall facing the plane ofprojection, is illustrated in FIG. 1.

The furnace chamber 3 is divided into three zones, namely into an inputzone 3E situated adjacent to the input side 5, a heating zone 3H thatfollows the input zone referred to the transport direction of the metalgoods 25 and a holding zone 3A that follows the heating zone referred tothe transport direction of the metal goods 25 and extends up to theoutput side 9.

The transport system for transporting the metal goods 25 through thefurnace chamber 3 comprises a fixed system of vertical beams andhorizontal support tubes 23, onto which metal goods 25 to be transportedthrough the furnace chamber 3 can be placed. The transport systemfurthermore comprises a lifting system 27, by means of which the metalgoods 25 can be lifted off the fixed system 23, advanced by a certaindistance in the direction of the output side 9 and then once againdeposited onto the fixed system 23 in accordance with the prior art.

The fixed system 23 defines a plane E, along which the metal goods 25can be transported through the furnace chamber 3.

The transport plane E divides the furnace chamber 3 into an upperfurnace 3 o and a lower furnace 3 u.

In order to fire the upper furnace 3 o in the region of the heating zone3H, the furnace 1 features roof burners 19 that are arranged on theceiling 13 in the region of the heating zone 3H. Alternatively, thefurnace 1 could also feature lateral burners 21 for firing the upperfurnace 3 o in the region of the heating zone 3H, wherein these lateralburners would be arranged in the region of the sidewalls and only thelateral burners 21 thereof arranged in the region of the sidewall 16shown are indicated with broken lines in FIG. 1. In order to fire theupper furnace 3 o in the region of the holding zone 3A, the furnace 1features end burners 17 that are arranged in the upper region of theoutput side 9. The furnace 1 features end burners 10 that are arrangedin the lower region of the output side 9 in order to fire the lowerfurnace 3 u in the region of the holding zone 3A.

In the region of the heating zone 3H, additional burners 29 are arrangedin the region of the furnace floor 15. These additional burners 29 areoriented toward the output side 9 such that parallel flames extendingtoward the output side 9 can be produced with the burners 29.

The additional burners 29 are arranged along a section that extendsparallel to the output side 9 and perpendicular to the plane ofprojection in the region of the furnace floor 15 such that only one ofthe additional burners 29 is visible in FIG. 1.

On its side that faces the furnace chamber 3, the furnace floor 15 formsa horizontal plane, the horizontal extent of which is not affected bythe additional burners 29.

The additional burners 29 are arranged in a housing 30 of a high aluminarefractory material and thereby effectively protected from the hotfurnace atmosphere.

The housing 30 is provided with flue gas supply means 31 in the form ofopenings that are arranged on the side of the housing 30 facing awayfrom the burner outlet of the burners 29. In this way, flue gas can beextracted from the region of the lower furnace space 3 u between theadditional burners 29 and the input side 5 of the furnace 3 through theopenings 31 and supplied to the additional burners 29 such that thisflue gas can be subjected to afterburning by the additional burners 29.

The height H of the lower furnace space 3 u, i.e. the clearance betweenthe transport plane E and the furnace floor 15, amounts to approximately2.5 m.

The clearance A between the upper side of the housing 30 and thetransport plane E amounts to approximately 1.3 m and therefore 52% ofthe height H of the lower furnace space 3 u.

Consequently, the remaining clearance A between the underside of thetransport plane E and the upper side of the housing 30 is sufficientlyhigh for allowing flue gases to flow from the region of the holding zone3A and the heating zone 3H in the direction of the input side 5 andtherefore through the input zone 3E of the furnace 1 without relevantflow resistance.

The furnace 1 furthermore features a walk-and service channel 33, fromwhich the additional burners 29 can be operated. The service channel 33is essentially arranged underneath the furnace floor 15 and allowspersonnel to access the housing 30 from the ceiling of the channel onlysuch that the burners 29 can be operated and serviced from the servicechannel 33.

FIG. 2 shows a highly schematic perspective view of the furnace 1according to the exemplary embodiment illustrated in FIG. 1 in theregion of the additional burners 29. In this case, the illustration inFIG. 1 is not true-to-scale referred to the illustration in FIG. 1.

The elongated shape of the housing 30 that extends over the furnacefloor 15 transverse to the longitudinal direction of the furnace 1 isillustrated particularly well in FIG. 2.

Having described the invention, the following is claimed:
 1. A furnacefor heating metal goods, comprising: a furnace chamber that is designedfor accommodating metal goods ; an input side with a furnace inlet ,through which metal goods to be heated in the furnace chamber can beintroduced into the furnace chamber; an output side with a furnaceoutlet, through which metal goods heated in the furnace chamber can beremoved from the furnace chamber; a ceiling that defines the top of thefurnace chamber between the input side and the output side; a furnacefloor that defines the bottom of the furnace chamber between the inputside and the output side; sidewalls that laterally define the furnacechamber between the input side and the output side; burners for firingthe furnace chamber, wherein the burners comprise at least one of thefollowing types of burners: roof burners arranged in the region of theceiling or lateral burners arranged in the region of the sidewalls;additional burners for firing the furnace chamber that are arranged inthe region of the furnace floor.
 2. The furnace according to claim 1,further comprising: a plane E, along which metal goods to be heated inthe furnace chamber can be transported through the furnace chamber,wherein the plane E divides the furnace chamber into an upper furnacespace that lies between the plane E and the ceiling and a lower furnacespace that lies between the plane E and the furnace floor; at least onehousing, in which the additional burners are arranged; wherein theclearance between the upper side of the at least one housing and theunderside of the plane E amounts to at least 40% of the height H of thelower furnace space.
 3. The furnace according to claim 1, furthercomprising a service channel that is arranged completely or essentiallyunderneath the furnace floor, wherein the additional burners can beoperated from said service channel.
 4. The furnace according to claim 1,further comprising a flue gas supply means, through which flue gases canbe supplied to the additional burners.
 5. The furnace according to claim1, further comprising: auxiliary burners for firing the furnace chamberthat are arranged in the region of the furnace floor; between theadditional burners and the input side.
 6. The furnace according to claim2, further comprising: a plane E, along which metal goods to be heatedin the furnace chamber can be transported through the furnace chamber,wherein the plane E divides the furnace chamber into an upper furnacespace that lies between the plane E and the ceiling and a lower furnacespace that lies between the plane E and the furnace floor; at least onehousing, in which the additional burners are arranged; wherein theclearance between the upper side of the at least one housing and theunderside of the plane E amounts to at least 40% of the height H of thelower furnace space.
 7. The furnace according to claim 2, furthercomprising a flue gas supply means, through which flue gases can besupplied to the additional burners.
 8. The furnace according to claim 2,further comprising: auxiliary burners for firing the furnace chamberthat are arranged in the region of the furnace floor; between theadditional burners and the input side.
 9. The furnace according to claim3, further comprising a flue gas supply means, through which flue gasescan be supplied to the additional burners.
 10. The furnace according toclaim 3, further comprising: auxiliary burners for firing the furnacechamber that are arranged in the region of the furnace floor; betweenthe additional burners and the input side.
 11. The furnace according toclaim 4, further comprising: auxiliary burners for firing the furnacechamber that are arranged in the region of the furnace floor; betweenthe additional burners and the input side.